Air valve for a pneumatic tool



Allg- 18, 1959 J. H. DALToN 2,899,935

' AIR VALVE FOR A PNEUMATIQ TooL Aug- 18, 1959 J. l-yl. DAL'roN 2,899,935

AIR VALVE FOR A PNEUMATIC TOOL Filed Feb. 12. 1957 2 Sheets-Sheet 2 United States PatentO AIR VALVE FOR A PNEUMATIC TOOL Joseph H. Dalton, Elmhurst, Ill., assignor to Signode Steel Strapping Company, Chicago, Ill., a corporation of Delaware Application February 12, 1957, Serial N0. 639,706

9 Claims. (Cl. 121-21) the head of the piston for an instant after the air valve has opened. In some of these tools the manual trigger for operating the valve also operates a piston release, and the combination of forces needed to open the valve against the inlet or line pressure of the air and to release the piston creates an objectionably high force to bey overcome in the trigger pull by the operator.

It is, therefore, an object of the present invention toprovide a new and improved air valve for pneumatic tools, and particularly those tools having holdup means on the air powered piston considerably to reduce the trigger pull required to open the valve and release `the,

piston. Y

Another object is to provide a new and improved air valve for pneumatically yoperated tools which opens in two steps, the rst step opening a small pilot valve to admit air to the underside of a larger valve to assist in thev second step of opening the larger valve.

Still another object is to provide a new and improvedV air operated tool having a two part air valve and a piston release pawl which are operated by a common trigger, the trigger having a rst range of movement to open a rst part of the valve, and a second range of movement to open the second part of the valve and to move the pawl to release the piston.

Still another object is to provide a new and improved air operated tool having the foregoing features, wherein the trigger pull is appreciably less for all line air pressures than would be the case in similar tools not equipped with the present invention. n

Other objects and advantages will become .apparent from the following description taken in conjunction with the accompanying drawings, wherein- Fig. i is a side elevational view, partially broken into section, of a pneumatically operated stapling tool incorporating the air valve, piston retaining pawl, Vand trigger mechanism of the present invention;`

Fig. 2 is a .fragmentary ,view illustrating the air'valv holdup pawl and trigger mechanism afterV thetrigger'has been moved through its first range` of niovement;:`

movement;

Fig. 4 is an enlarged detail view taken alongrthe line 4-4 of Fig. 1, looking in thedirection of the arrows;

Fig. 5 is an enlarged horizontal sectional View taken along the line 5-5 of Fig. 4, looking in the directionof the arrows;

Fig. 6 is a detail sectional view similar to Fig 4 of-a modied form' of valve member; and

n 2,899,935 Patented Aug. 1s, 1959 ICC Fig. 7 is a detail sectional view of the modified Valve member taken on a medial plane at right angles to that of Fig. 6.

' The present invention is illustrated and described in conjunction with the pneumatic stapling tool shown and described in greater detail in thecopending application of Arvid I. Ericsson, Serial No. 621,096, filed November' 8, 1956, ventitled Pneumatic Stapling Tool and assigned to theassignee of this invention. It is to be understood, however, that the principles of this invention may be applied to'other pneumatically operated, manually trig' gered tools, where high impact is desired. i

Thepneumatic stapling tool in which the present invention is incorporated isindicated generally by the reference character 10 vand includes a main body casting 12 providing a handle portion 14 and an air cylinder 16, and

' a staple magazine 18 secured to the casting 12. In the handle portion of the casting there are formed an air inlet passage 20, and an air exhaust passage 22, the inlet passage 20 being tapped at its outer or inlet end 24 toV receive a fitting to. which the conventional air supply hose (not shown) may be connected. The tool also includes a nose assembly 26 at the forward end of the magazine 18 and below the air cylinder 16, which is adapted to be held against. the work and through which the staples are vention. A return spring v36 biases the piston 32 to re-A tracted position, and a cushion 38 is positioned in the lower end of the cylinder 16 to absorb the impact'of the piston in vthe event that the tool is operated with little or no resistancein driving the staples, as is the case in clear` ing the staple guideway by ring the tool in the air.

The casting 12 is formed with an air passageway 40 which ycommunicates with the upper end of the cylinder 16 throughports 42 in the cap 28 defined between the stops 30. At its opposite end the passageway 49 communicates with a valve 44 which is constructed in accordance with the present invention.

The piston 32 is momentarily detained in its power stroke after aii has been admitted to the upper end of the cylinder 16 by a retaining pawl 46 which is pivotally mounted on a pin48 bridging a slot 50 formed in the side wall of the cylinder 16 below the position or" the -piston 32 in its retracted position. The pawl 46 has av movement1when the piston is in its retracted position Fig. 3 is a viewvsimilar to Fig.2, but showing the valve in fully open position and the pawl released fromthe piston'at the end of the second range Aofvtrigger l The pawl 46 is moved from piston engaging position, Y as shown-progressively in Figs. 1, 2 and 3, by a trigger 64 whichA has a hub portion 66 projecting -intothe slot 59,-

and pivotally mounted on the pin 68 which extends across the slot. The trigger 64 has a forward edge portion 7@-V engageable withthe tail 72 ofthe pawl 46 and has a linger' portion 74 engageable with'the valve 44, to operate the latter, as will be clear hereinafter.

,The valve 44 is located in a cored passageway 76 which communicates with the inlet, passageway 20, the exhaust passageway 22, and the connecting passageway 3 40, and therefore the valve 44 controls the flow 0f compressed air into the exhaust of air from the cylinder 16.

The valve 44 includes a valve sleeve 78 having an inlet port 80 surrounded by a valve seat 82, a port 84 communicating with the passageway 40, and an exhaust port 86 communicating with the exhaust passage 22. sleeve 78 is secured by a roll pin 88 and sealed against the casting 12 by gaskets or O-rings 90.

The valve 44 includes a first and ring-like valve member 92 havinga sealing'O-ring 94 fixed in a groove therein and adapted to seal against the valve seat 82 in the valveV inlet 80. The ring valve member 92 also provides a conical seat 96 which is of smaller diameter than the seat 82 and which surrounds an `inlet port or passage 98 through the ring valve member 92.

The valve 44 includes a'second valve member 100 which has a valve head 102 fitted with a sealing gasket or O-ring 104 which is adapted to seal against the valve seat 96. The valve head 102 is secured to a valve stem 106 which is formed atV its lower end with a valve p-iston 108 slidable in a bore 110 in the sleeve 78 and controlling the exhaust 4air flow through the port 86.

Between the head 102 and the piston valve 108 the valve stem 106 is considerably smaller in diameter than the port 98 and the major diameter bore 112 `in the sleeve 78. However, at or adjacent its upper end the stern 106 is provided with a pair of sidewardly extending shoulders 114 `which are formed on the upper face of a circumferentially projecting annulus or ridge 116 integral with the stem 106. The annulus is cut or milled away at 118 to define t-he shoulders 114 at diametrically opposite sides of the stem 106, the cutaway sections being opposite each other and milled to the diameter of the stem 106.

The lower end of the piston valve member 108 projects from the bottom of the sleeve 78 and normally engages the finger grip 74 of the trigger 64 and when the valve is closed biases the trigger toward a stop 120 which is positioned below the pivot 68.

During the operation of the valve from closed to open position, the trigger 64 is moved or pivoted toward the grip 14. The valve member head 102 moves away from the ring valve seat 96, thereby opening the port or passage 98 through the ring valve member 92, and the valve piston 108 closes the exhaust port 86. As the stem 106 moves upwardly, the shoulders 114 on the annulus` 116 contact the underside 122 of the ring valve member 92 to lift it off the seat 82. However, the ow of air through the passage 98 is not interrupted as the annulus 116 nears and engages the valve member 92, because it flows through the openings provided by the Ymilled portions 118.

The operation of the tool incorporating the novel valve 44 of the present invention is `as follows: Assuming that the valve 44 is closed, that the piston 32 is in retracted position, and that a staple has been moved into the guideway (not shown), the operator places the nose assembly 26 against the work and squeezes the trigger 64 toward the handle 14. The movement of the trigger in its rst range of movement from the position shown in Fig. 1 to the position shown in Fig. 2, does three things. Initially, the Valve member 100 is moved upwardly from its closed position (Fig..1) sealing against,

the seat 96 to open position (Fig. 2), thereb-yfopening the port or passage 98 through the large valve member 92. This movement brings the annulus shoulders 114 against the underside 122 of the larger valve member 92. The valve piston 108 closes the exhaust port 8,6. yAt the same time the forward edge 70 of the trigger 64 contacts the tail 72 of the pawl 46 and moves it slightly from the position shown in Fig. Vl, where the lip 56 engages the side wall of the piston 32 to the position shown in Fig. 2 where this lip 56 is moved very slightly away from the Thev 4 v l of the piston 54 remains in engagement with the lip 52. The piston 32 moves slightly downwardly away from the stops 30, since air under pressure has entered the cylinder 16, but further movement is prevented by the engagement of the underside 54 of the piston 32 withl the pawl lipI 52.

As soon as the valve 100 opens, air at line pressure passes through the port 98. This produces, in addition to pressure in the cylinder 16, pressure at the underside of the ring valve member 92 opposing the line pressure at the face of this valve member. Therefore, when the trigger 64 `is moved through its second range of movel ment and against the handle 14 (Fig. 3), the air pressure at the underside of the valve member 92 adds its force to that applied through the valve stem 106 and shoulder to unseat and open the valve member 92. At the same time the forward edge 70 of the trigger 64 pivots the pawl 46 further in the clockwise direction sufciently to move the lip 52 out from under the underside of the piston 32. Air under considerable pressure has built up in the cylinder 16 while the pawlV 46 detained the piston 32 from its power stroke, and therefore the piston 32 moves through its power or working stroke with considerable force and a hammerlike blow.

In this description the trigger 64 has` been described as having two ranges of movement. This nomenclature has been adopted for convenience herein, because the operator normally will quickly squeeze the trigger 64 Y 92 and 100 to closed position.

vThere is no critical relationship in the sizes` of the` valve members 92 `and 100. It is desirable, however, that the valve member 100 have suficient area exposed to the inlet or line pressure to give the trigger 64 some feel during the initial movement of the valve member 100 to open the port 98 in the valve member 92. The valve structure shown in the-drawingsV has a valve 100 with an effective area of about one-third that of the combined area of the valve members 92 and 100. Therefore, about 1 one-third the pressure is required to open the valve mempiston. It will be observed, however, that the underside ber as would be required toopen a larger valve having an area equal to that of the valve member 92.

The diameter of the valve piston 108 is theoretically important. The diametral relationship between the ring valve member 92 and the valve piston 108 should be such that the diameter of the valve piston is small enough to minimize the effect of the secondary inlet air pressure acting on its area but still large enough to provide adequate exhaust ow. In the particular valve shown the diameter, but not the area, of the valve piston 108 is approximately the same as` that of the valve member 100 exclusive of the sealing ring 104.

In Figs. 6 and 7 there is shown a modification of the v valve 44 wherein second valve member 122` is formed v differently than Vthe valve member 100 of the form shown in Figs. 1 to 5. The valve member 122 has a head 124` having a major diameter to permit the valve head to have a sliding iit in the passage 98 of the ring valve 92. Adjacent its upper end the head 124 is formed with an annular groove 126 in which is retained the O-ring 104 which seals against the ring valve seat 96.

At the lower end of the valve head 124 the valve member 122 is formed with an outstanding annulus or yridge 128 of larger diameter than the head 124 and which` defines on its upper surfaces shoulders 130 to engage and unseat the ring valve 92 during the second stage of the valve opening movement.

Between the O-ring 104 and the edge 12S the valve head 124 is milled at diametrally opposite sides 132 to produce ports'135 between the head and the ring valve 92. The ports 135 are completed by the milled surfaces 134 on the ridge 128. f

The functioning of this modification .is precisely the same as that of the form shown in Figs. l to 5. However, the valve head 124 fitting .closely with the ring valve 92I prevents misalignment of the ring valve during operation of the tool.

It is clear, therefore, that with this valve assembly it is possible to open the valve 44 with a minimum of effort and to allow pressure to begin its build-up in the cylinder 16 before effort is used to release the-pawl 46 from the piston 32. In fact, the trigger pull required to operate the tool equipped with the valve 44 is less than half that which would be required to operate a similar tool at similar pressures having a single valve member in place of the double valve 44. v

The objectives whichwere claimed for this invention at the outset of this specication have clearly been attained by the structure disclosed.

While a preferred embodiment of the air valve for pneumatic tools constituting the present invention has been shown and described, it will be apparent that numerous modifications and changes may be made therein without departing from the underlying principles ofthe invention. It is, therefore, intended by the-following claims to include all such variations and modifications by which substantially the results of this invention may be obtained through the use of the same or equivalent means.

What is claimed as new and desired to be secured by United States Letters Patent is: v

l. A valve for a pneumatic tool adapted to control the flow of air under pressure to and from an air motor and to be positioned between an air motor and an air inlet and an air exhaust,'comprising in combination, a sleeve providing a first valve seat open toward the air inlet and having a port communicating with the air motor and an exhaust port communicating with the air exhaust, said ports normally communicating with each other through the interior of said sleeve, a first Valve member coacting with and sealing against said valve seat, said first valve member comprising an annulus and providing a second valve seat open toward the air inlet, said annulus having a single passage therethrough from said seat to communicate the air inlet with the underside thereof, a second valve member having a head portion subject to inlet air pressure sealing against said second valve seat and a stem projecting through said passage in spaced relation to said annulus, said second valve member having a piston portion connected to said valve stem, slidable in'said sleeve and adapted to close said exhaust port, trigger means engaging said second valve member and adapted to be moved so as to move the latter to open the valve at the air inlet and simultaneously to close the valve at the air exhaust, and annulus lifting shoulders on said valve stem and positioned to engage the underside of said annulus after said head portion has been unseated initially to open the valve and to admit air under pressure to the air motor and said second valve member has been moved a predetermined distance and said piston portion has `closed said exhaust port.

2. In a pneumatically operated tool having an air inlet and an air motor with Va piston movable in a cylinder, comprising in combination, movable piston detaining means engaging the piston in retracted position to detain its movement under air pressure, means forming a valve seat open toward the inlet and having a port com-- municating Vwith the cylinder at the head of the piston, a first valve member coacting with and sealing against said valve seat and movable in a first direction toward open position, said rstf .valve member rhaving a passage therethrough Vcommunicating the inlet with theunderside` of4 said first lvalve member, a second valve member normally closing said passage and being movable in the same direction as said first valve member to open said passage, means connected to said second valve member and movable vto open said second valve member, first Valve lifting means on said movable means and engageable with said first valve member after said second valve member. has been moved to open position and said movable means has been moved a predetermined distance thereby to open said second valve member upon continued movement of said movable means in valve opening direction, and trigger means engaging said movable means to move lit in valve 'opening direction and engageable with said piston detaining means to move it from engagement with the piston after said second valve member has .been opened.Y

3. In a pneumatically operated tool having an air inlet, a cylinder, and a piston slidable therein, comprising in combination, a pivotally mounted pawl engaging the piston in retracted position to detain its movement underv air pressure, means forming a valve seat open toward the inlet and having a portcommunicating with the cylinder at the head of the piston, a first valve member coacting with and sealing against said valve seat and movable in a first direction toward open position, said first valve member being ring-shaped and providing a second valve seat. opentoward the inlet and a .passage therethrough from said second valveV seat to the underside thereof, a second valve member having a head portion sealing against said second. valve seat and a stem projecting throughl said passage, .trigger means engaging said valve stem and adapted to bemoved so as to move said valve stern in valveopening direction, ringvalve lifting means on'saidvalve stem and positioned'to engage the underside of said ring-shapedvalve member to unseat the latter after said second valve member has been unseated and said valvestem has been moved a predetermined distance bysaid trigger means, and means on said trigger means engageablewith said pawl and moving said pawl from piston detaining position afterfsaid trigger means has moved said valve stem said predetermined distance.

4. In a pneumatically operated tool having -an air inlet,

the .combination comprising', means forming a cylinder,

a piston slidable in said cylinder and biased to retracted position, a piston movement detaining pawl movably mounted on` said cylinder` forming meansA and biased into engagement with said piston in retracted position, an air valve controlling the `admission of air into-said cylinder, said air valve including means forming a first valve seat open to an airinlet and a port communicating with said cylinder, a ring valve member sealing against said first valverseat and providing a second -valve seat smaller than said. first valve seatand having afpassage therethrough from said secondvalve seat, a second Valve member sealing against said second valve seat, a .valve stem kconnected to said second valve .member and projecting through said passagek in spaced relation thereto, ring valve lifting means` on said valve stem and adapted to engage the underside of said'ring valve after said second valve member has been moved to open position, V.and manual valve operating means movably mounted relative to said means forming said'cylinder and to said air valve, said manual means being engageable with said pawl and with said valve stem, said'manual means being movable first to unseat said second valve member to admit air to said cylinderandto the underside-of said ring valve and then to unseat saidring valve and to move said pawl to release said piston. Y

5. In a pneumatically operated tool'having an air inlet, the combinationcomprising, an airmotor having a cylinder forming means and a piston 'slidable in said cylinder and biased to retracted position, a piston movement detaining pawl pivotally mounted on said cylinder *form/J ing-means and biased into-,engagement withl Ysaid piston in retracted position, an air'valve controlling the admission of air into said cylinder, said air valve including means forming a first valve seat open to an air inlet and a port communicating with said cylinder at the head of said piston, a ring valve member sealing against said first valve seat and providing a 4second valve seat and a passage from said second valve seat to the underside thereof, a second valve member sealing against said second valve seat, a valve stem connected to said second valve member and projecting through said passage in spaced relation thereto, and Vring valve lifting shoulders on said valve stem and positioned to engage the underside of said ring valve after said valve stem has been moved a predetermined distance, and a trigger pivotally mounted relative to said cylinder forming means and said air valve, said trigger having a part engageable with said pawl and a part engageable With said valve stem, said trigger beingvmovable through a first range of movement to lunseat said second valve member Vto admit air to said cylinder and to the underside of said ring valve and to engage said pawl and being movable through a second range of movement to unseat said ring valve and to pivot said pawl to release said piston.

6. In a pneumatically operated tool having an air inlet, the combination comprising, an air motor having a cylinder forming means and a piston slidable in said cylinder and biased to retracted position, a pawl pivotally mounted on said cylinder forming means and engageable With the underside of 4said piston to detain it from movement from `retracted position, means biasing said pawl into piston engaging position, an air passage cornmunicating with said cylinder at the head of said piston, an air valve controlling the admission of air into said cylinder, said air valve including a sleeve forming a first valve seat open to an air inlet and a port communicating with said passage, a ring valve member sealing against said first valve seat and providing a second valve seat smaller than said first valve seat, `a second valve member having a head sealing against said second valve seat and a valve stem projecting through said ring valve member in spaced relationV thereto, and said valve stem having ring valve lifting shoulders thereon adapted to en-V gage the underside of said ring valve after said valve stem has been moved a predetermined distance, and having an end projecting from said sleeve opposite said first valve seat, and a trigger pivotally mounted relative to said cylinder forming means and said air valve, said trigger having a part engageable with said pawl and a part engageable with said projecting end of said valve stem, said trigger being movable through a first range of movement to unseat said second valve member to admit air to said cylinder and to the underside of said ring valve and to engage said pawl and being movable through a secondl range of movement in the same direction as said first range of movement to unseat said ring valve and to pivot said pawl to release said piston.

7. In a pneumatically operated tool having an air inlet and an airexhaust, the combination comprising, an air motor having a cylinder forming means, a piston slidable in said cylinder, and means biasing said piston to retracted position, a pawl pivotally mounted on said cylinder forming means and having a lip engageable With the underside of said piston, means biasing said pawl into piston engaging position, an air passage communicating with said cylinder at the head of said piston, an air valve controlling the admission of air into and the exhaust of air from said cylinder, said air valve including a sleeve forming a first valve seat open to the air inlet, a port communicating with said passage and an exhaust port communicating with the air exhaust, a ring valve member sealing against said first valve seat and providing ka secondvalve seat smaller than said first valve seat, a second valve member having a head lsealing against said second valve seat and a valve stem projecting through said ring valve member in spaced relation thereto, and

said valve stem having ring `valve member lifting shoulders thereon adapted to engage the underside of said ring valve after said valve stem has been moved a predetermineddis/taance Vto open said second valve member, said stem'havin'g a piston portion controlling ow through said exhaust port and having an end projecting from said sleeve opposite said first valve seat, and a trigger pivotally mounted relative to said cylinder forming means and said air valve, said trigger having a part engageable with said pawl and apart engageable With said projecting end of said valve stern, said trigger being movable through a first range of movement to unseat said second valve member to admit air to said cylinder and to the underside of said ring valve and to engage said pawl and being movable through a second range of movement in the same direction as said first range of movement to unseat said ring valve and to pivot said pawl to release said piston.

8. In a pneumatically operated tool having an air inlet and an air exhaust, the combination comprising, an air motor having a cylinder forming means, a piston slidable in said cylinder, and means biasing said piston to retracted position, a pawl pivotally mounted 011 said cylinder forming means and having a lip engageable with the underside of said piston in retracted position, means biasing said pawl into piston engaging position, an air passage communicating With said cylinder at the head of said piston, an air valve controlling lthe admission of air into and the exhaust of air from said cylinder, said air valve including a sleeve forming a rst valve seatopen to an air inlet, a port communicating with said passage and an exhaust valve cylinder'at said exhaust port, an exhaust port communicating With the ai'fr exhaust, a ring valve member sealing against said rst valve seatand providing a second valve seat smaller than said first valve seat, and a passage therethrough from said second valve seat, a second Vvalve member having a head sealingfagainst said second valve seat, a valve stem connected .to said head and projecting through said ring valvepassQ-age in spaced relation thereto, ring valve lifting shoulders on said valve stem and positioned to engage the underside of said ,ring valve after said val-ve stem has been moved a predetermined distance, and a valve piston connected to said valve stem slidable in said exhaust valve cylinder and controlling iiow through said exhaust port and having a portion projecting from said sleeve, and Va trigger pivotally mounted relative to said cylinder forming means and said air valve, said trigger having a part engageable with said pawl and a part engageable with saidprojecting piston portion, said trigger being movable through a iirst range of movement to unseat said second valve member to admit air to said cylinder and to the underside of said ring valve and to engage said pawl and being movable through a second range of movement to unseat said ring valve and to pivot said pawl to release said piston.

9. A valve for a pneumatic tool adapted to control the iiow of air under pressure to and from an air motor seat open toward the air inlet, said annulus having'ar, single passage therethrough from said valve seat to com-'- municate the air inlet with theunderside thereof, a second valve member having ahead portion subject to inlet air pressure and slidably projecting through said passage, means on said head portion sealing against said sec-' ond valve seat, said head portion being formed at oppo-v site sides with flatted faces to form with said passage ports through said annulus when said sealing means is unseated from said second valve seat, said second valve member having a valve stem connected to said head portion, said second valve member having a piston por tion connected to said valve stem and slidable in said sleeve, said piston portion projecting from said sleeve opposite said val-ve seat and adapted to close said exhaust port when said sealing means is unseated from said second valve seat, trigger means engaging said piston portion and adapted to be moved so as to move said second valve member simultaneously to open said passage through said annulus, and to close said exhaust port, and annulus lifting shoulders at the juncture of said head portion and said valve stem to engage the underside of 15 2,729,198

said annulus after said sealing means has been unseated and said second valve member has been moved a predetermined distance.

References Cited in the le of this patent UNITED STATES PATENTS 175,558 Haviland et al. Apr. 4, 1876 453,785 Howes June 8, 1891 1,498,226 Beck June 17, 1924 1,821,206 Caswell Sept. 1, 1931 2,241,184 Clark May 6, 1941 2,467,546 Anderson Apr. 19, 1949 2,713,165 Campbell et al July 19, 1955 Faccou Jan. 3, 1956 

